This invention relates to a phosphor, and more particularly to a phosphor having a diamond-like carbon film deposited thereon and a display device having such a phosphor incorporated therein.
A phosphor has been conventionally incorporated in various kinds of display devices. For example, a fluorescent display device includes an envelope which is kept at a high vacuum and in which electrodes such as phosphor-deposited anodes, electron emitting cathodes and the like are arranged so as to permit electrons emitted from the cathodes to be impinged on phosphor layers, leading to display of desired luminous colors. Such a fluorescent display device or the like has a variety of phosphors incorporated therein depending on a purpose thereof. Of such various phosphors, phosphors mainly consisting of elements belonging to Groups II-VI of the periodic table such as, for example, a phosphor mainly consisting of sulfide (sulfide phosphor), a phosphor mainly consisting of Sr (Sr phosphor), a phosphor mainly consisting of Y (Y phosphor) and the like exhibit an increased surface activity, to thereby cause gas remaining in the envelope such as H.sub.2, H.sub.2 O, O.sub.2 or CO.sub.2 adhered to an inner surface of the envelope to be adsorbed on a surface of the phosphors, resulting in luminous efficiency of the phosphors by excitation due to impingement of electron beams thereon being deteriorated. In order to prevent such adsorption of gas on the surface of the phosphor and also protect the phosphor, it has been often carried out to coat a SiO.sub.2 film on the surface of the phosphor. Such coating of the SiO.sub.2 film is known in the art as a surface treatment for a phosphor used for, for example, a cathode ray tube or the like.
Unfortunately, Si in the form of a thin film is active, so that the SiO 2 film actually adsorbs gas thereon, resulting in failing to sufficiently protect the phosphor.